The present invention relates to a technique of sharing presence information in instant messaging.
Recently, a technique of instant messaging (so-called text chat) for sending an inputted text to another terminal in real time is rapidly coming into wide use (See NIKKEI COMMUNICATION 2003.9.22, P150-P158, “Technical Commentary—SIP (Session Initiation Protocol)” (hereinafter, referred to as “Non-patent Document 1”)). Although it is needless to say that the technique of instant messaging is used for personal purposes, various methods are being studied for applying this technique in business situations such as communication from a staff member on a business trip, an online conference for a project, and the like. The technique of instant messaging employs SIMPLE (SIP for instant Messaging and Presence Leveraging Extension), which is an extension of SIP (Session Initiation Protocol). SIP is prescribed in RFC3261 issued by a standardization group, IETF (Internet Engineering Task Force).